Re: Proposal: Implement failover on libpq connect level.
| От | Amit Kapila |
|---|---|
| Тема | Re: Proposal: Implement failover on libpq connect level. |
| Дата | |
| Msg-id | CAA4eK1LvugdRvXbEw_o7OSddVBRH8LD7s8qrwO3Z3gUfcpuG0Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Proposal: Implement failover on libpq connect level. (Victor Wagner <vitus@wagner.pp.ru>) |
| Ответы |
Re: Proposal: Implement failover on libpq connect level.
|
| Список | pgsql-hackers |
On Wed, Aug 19, 2015 at 1:23 PM, Victor Wagner <vitus@wagner.pp.ru> wrote:
>
> On 2015.08.19 at 12:55:15 +0530, Amit Kapila wrote:
>
> > > I think that failover procedure should begin before first connection is
> > > ever established.
> > >
> >
> > As far as I understand, failover gets initiated once the master server goes
> > down or is not accessible due to some reason, so for such cases if you
> > have the connection to both the servers then it might not work.
>
> Master server might go down when client is not started yet.
> And when client starts up, it has to find out which server to connect
> now.
>
>
> On 2015.08.19 at 12:55:15 +0530, Amit Kapila wrote:
>
> > > I think that failover procedure should begin before first connection is
> > > ever established.
> > >
> >
> > As far as I understand, failover gets initiated once the master server goes
> > down or is not accessible due to some reason, so for such cases if you
> > have the connection to both the servers then it might not work.
>
> Master server might go down when client is not started yet.
> And when client starts up, it has to find out which server to connect
> now.
>
Always try with the first server specified in connection string and if that
is not available try with second and so on. I think for the case of failover,
the design shouldn't be much complicated and it is a standard thing provided
by most of the client-side drivers in other databases. Considering what
currently PostgreSQL offers in terms of high-availability functionality, for
load-balancing, we need to be careful of many more things like redirecting
read-queries to standby's, write statements should be executed via connection
to master.
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